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The Ocean. By: Mary Rose Lunde. Coral Reefs. Coral Reef. Known as the “rainforest of the ocean,” coral reefs are home to 25% of the ocean's marine life but only account up for 1% of the marine environment
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The Ocean By: Mary Rose Lunde
Coral Reef • Known as the “rainforest of the ocean,” coral reefs are home to 25% of the ocean's marine life but only account up for 1% of the marine environment • Found in clear, shallow, warm waters where sunlight provides nutrients to the algae that sustain coral. • Coral reef provide protection to coastal communities form hurricanes • Chemical compounds extracted from coral are used in medicine for cancer, AIDS, and other diseases. • Coral reefs are extremely vulnerable to warm water temperatures. • When water temperature rises, the algae living in coral dies, creating large areas of dead, bleached coral reefs. Global warming means that events like the catastrophic 1998 coral bleaching in the Great Barrier Reef in Australia will become more commonplace in the future. An increase of greenhouse gases in the atmosphere also leads to more acidification of ocean waters which can harm coral and inhibit the production of coral reefs.
Coral organisms, called polyps, are actually tiny invertebrate animals usually ranging from 1-3mm in size. • Coral polyps are classified as anthozoans within the phylum of Cnidaria. Anthozoansare characterisedby a radially symmetrical body with a single opening (which serves as a mouth and anus) surrounded by tentacles. • Tentacles contain venomous cells known as nematocyst and are used by the polyp to capture prey. • The mouth of the polyp leads into the gastrovascular cavity, a simple sac-like stomach, where food is digested. • The gastrovascular cavity, lined by the gastrodermis (stomach lining), is divided into a number of chambers by a series of the vertical plates (septum, pl. septa). • These plates support the internal stomach folds, known as mesenteries, which increase the surface area of the stomach thereby aiding the digestion of food. The gonads of polyps are also found in the mesenteries. • The top of the coral is covered with a mucus layer. The outer tissue surface of the polyp that is in contact with the water is called the epidermis. Between this surface and the gastrodermis (stomach lining) lies the mesoglea, a jelly-like connective tissue. • Each coral polyp is connected to its neighbour by the coenosarc tissue.
Hard corals (hexacorallia or hexacorals) • The tentacles, septa and mesenteries in hard corals appear in multiples of six hence the name hexacorals. • Hard corals are commonly referred to as ‘reef builders’ due to the calcium carbonate skeletons they secrete. The skeleton deposited by an individual polyp is known as a corallite. These corallites, are incorporated in the anatomy of coral polyps. For example, as a hard coral secretes calcium carbonate, a cup or calyx is produced, the walls of which are called theca. At the bottom of this cup is the basal plate tissue and it is upon this plate that the coral polyp sits. hard coral polyp (hexacorallia) b) a withdrawn hard coral polyp c) an empty coral cup or calyx.
Soft corals (Octocorrallia) • Unlike hard corals, the mesenteries and tentacles of a soft coral polyp are found in groups of eight hence the name octocorrallia or octocoral. • Few soft coral polyps secrete calcium carbonate skeletons therefore their polyps do not contain septa, calyx, theca, or basal plate. • Although soft corals lack the rigid calcium carbonate exoskeleton (external skeleton) of hard corals, their tissue structure has some strength and can appear rigid as it is supported by a series of calcium carbonate bodies known as spicules.
Corals and zooxanthelle: a symbiotic relationship • Some species of hard and soft corals, known as hermatypic corals, host a type of algae known as zooxanthelle within in their gastrodermal cells. • While the coral tissue protects the zooxanthelle from herbivorous grazers, the zooxanthellephotosynthesises to produce energy which they then share with their coral hosts. • As the coral polyps gain extra nutrients from the zooxanthelle, the energy produced via their own feeding activity can be stored or used in high-energy activities which contribute to reef growth such as reproduction and the secretion of calcium carbonate skeletons. • As well as producing energy for their host corals, the zooxanthelle use many of the polyps’ waste products such as carbon dioxides, nitrogen and phosphorus. The benefits of this relationship are felt by both the symbiontzooxanthelle and coral polyp therefore it is known as a mutualistic symbiotic relationship.
Agnatha(Jelly fish) • Representatives: Sea Lamprey, hagfish • General features: no jaws, unpaired fish, eel-like bodies, notochord persists, cartilage skeleton • Integument: no scales, smooth, slimy skin • Circulatory System: 2 chambered heart • Movement: lamprey swims in arippling manner • Reproduction: external fertilization lamprey - larva, metamorphosis
Chondrichthyes(Cartilagenous fish) • General features: movable jaws, paired fins, cartilage skeleton • Integument: placoid scales (tooth-like), like sandpaper (no overlap), lateral line (pits sense movement) • Food getting and digestion: predator of fish, mollusks + lobster; triangular teeth continuously shed +replaced • Respiratory system: gills • Movement: shark - streamlined body + paired fins, move by moving tail and trunk side to side • Reproduction: shark - internal fertilization some are born alive, others lay fertilized eggs in capsule
Osteichthyes (Bony Fish) • Representatives: salmon, trout, eel, hake, tuna, seahorse • General features: largest class, movable jaws, paired fins w bony ribs, bony skeleton • Integument: protective, overlapping, scales, lateral line • Food getting and digestion: various modes; typical GI tract + glands: liver, gall bladder, pancreas • Respiratory system: gills covered by operculum • Movement: paired fins, side 2 side, movement of tail + body, swim bladder (depth) • Reproduction: external fertilization eggs + milt
How Gills work • http://www.youtube.com/watch?v=cVFqME-NW9s • A gill is a respiratory organ that extracts dissolved oxygen from water and excretes carbon dioxide • Some gills have adapted to allow respiration on land as long as they are kept moist. • Surface area is key to the exchange between the water and the absorption of oxygen in the water since water only carries a small portion of dissolved oxygen. • Gills usually consist of thin filaments of tissue, branches, or thin lamellae(folded) surfaces to increase surface area. • These filaments contain blood or coelomic fluid where gases are exchanged in the walls • Blood carries oxygen to parts of the body while carbon dioxide diffuse through the gills into the water • Gills are located in different parts of the body and are found in in animals such as: mollusks, crustaceans, insects, fish, and amphibians.
Benthic Zone • The bottom of the body of water, which is inhabited by benthos. • Benthos have a close relationship with the substrate bottom and may live attached to the ocean floor. • The superficial layer of the soil lining the given body of water, the benthic boundary level influences the biological activity which takes place there. • Examples include sand bottoms, rocky outcrops, and coral
Pelagic Zone • That part of a lake, sea, or ocean that is the habitat of pelagic organisms—plankton, nekton, and pleuston. In oceans and seas, the pelagic zone is divided horizontally into two regions: the neritic (water above the shelf) and the oceanic (all the remaining water). • Vertically, the zone is divided, usually depending on the degree of illumination, into three regions: the euphotic, dysphotic, and the aphotic. The zone is also broken down according to the distribution of life into the epipelagic, mesopelagic, and deep-water regions. • Animals in this zone include: cetaceans(whales, dolphins, porpoises) and large fish such as bluefintuna, and invertebrates such as jellyfish. • In the deeper areas there are giant squid, prime food for the deep-diving sperm whale.
Photic Zone (known as Epipelagic zone) • The surface layer -extends from the surface to 200 meters (656 feet). • known as the sunlight zone because this is where most of the visible light exists. • Heat(light) is responsible for the wide range of temperatures that occur in this zone. • Most fish and plankton live in this zone • Because photosynthesis occurs here, more than 90 percent of all marine life lives in the sunlit zone.
Dysphotic Zone (Twilight Zone) • Small amount of light can penetrate the water at this depth. As the water becomes deeper, the pressure increase.Plants do not grow here. Only animals that have adapted to little light survive. • Animals that live in the twilight zone include: lantern fish, rattalk fish, hatchet fish, viperfish, and mid-water jellyfish. • This murky part of the ocean begins at about 600 feet under the water and extends to the darkest part, which begins about 3,000 feet down. • Some squid and fish can use their bodies to make light. These creatures are said to have bioluminescence.
Aphotic Zone (Midnight Zone) • Ninety percent of the ocean is in the midnight zone. It is entirely dark—there is no light. The water pressure is extreme. The temperature is near freezing. • The living things found here live close to cracks in the Earth's crust. These cracks give off mineral-rich materials from the Earth itself. • Special forms of bacteria utilize hydrogen sulfide from the cracks for energy to make food. All other living things in the aphotic zone are nourished by these bacteria. • Living things in the midnight zone include: angler fish, tripod fish, sea cucumber, snipe eel, opposom shrimp, black swallower, and vampire squid.
Plankton • Small floating organisms (plant or animal) that are carried by the tides, winds, and currents • Either Zooplankton (animal like) or phytoplankton(plant like) • Phytoplankton are usually algae or diatoms • Din0flagellates (plants and animals) responsible for “red tide” • Zooplankton- Meroplankton(part) Holoplankton(full) • Nanoplankton- microscopic/unicellular • Microplankton-usually egg or larva stage • Macroplankton-1mm copopods • Megaplankton- mostly jellyfish
Nekton • Strong swimming animals that live in the open ocean not affected by tides, wind, or currents • Animals capable of swimming powerfully (including squid) • Adapted to swimming long distances but prefer one area because they can’t adapt to environmental changes
Benthic • Organisms that live on the ocean floor (plant or animal) • Epiflora(plant) and epifauna(animals) on or in the bottom • Infauna- animals buried in the ocean floor • Larvae form important part of meroplanktonthis valuble food source • Examples: sea fan, sponges, coral, crab, muscles, and sea weed
